Excluding and Rust 
Inhibiting Properties of 
Paint Pigments for the 
Protection of Steel and 



= Iron 



By HENRY A. GARDNER 

Director Scientific Section, Bureau of 

Promotion and Development, Paint 

Mantifacturers* Association of 

the United States 

3500 Grays Ferry Road, Philadelphia 



PRESENTED BEFORE THE FORTIETH ANNUAL CONVEN- 
TION OF THE MASTER CAR AND LOCOMOTIVE PAINT- 
ERS* ASSOCIATION OF THE UNITED STATES & CANADA 



NIAGARA FALLS, NEW YQRK, 5 



BER 14th, 1909 



Copyritf 




Class T A. ^ & '•( 



/■'•\ 



Book. -^ "^ 



Copyright}!?- 



COPyRIGHT DEPOSm 



ERECTED, RA.INTED AND EXPOSED. 

OCT le, NOV le, 1908. 

LOCATtON- DOVER AND VEIVTNOR. AVES. 



DIA^GRAIMI 

PAIIVT TEST-STEEL FENCE 
A.TLA.IVTIC CITY, JV. J 



H.A.GARDNER 
I>I HECTOR OF TEST 
SCIENTIFIC SECTION 
PA.1NT MANUSHCTDRERS ASSOCIATION 















































































FENCE 


NO 1 






















































I 


/ 


I 


^ 


I 


3 


I 


■* 


I 


s 


I 


6 


I 


7 


I 


9 


I 


/O 


1 /2 


I /* 


r /s 


I 


/« 


I 


/7 


I /9 


r ^<3 


1 




I 2<» 


I 27 


I 


i-S 


I ^9 


I 3C 


X J/ 


I 32 


r Jj 


I JM " 


I 3S 


I ss> 


I <<J 


I "// 


I -*4 


I ts 


1 ■#* 


1 


■*9 


I S/ 


/// 


I s 
zzz 


I c 
333 




1 c 
sss 


I c 


I c 

777 


I c- 




I c 

3000 


I c 




lOO 


90 


90 




'000 t'Sf.p 






















































































TRCNT 

























































r £ 



jr~5 



I 7 



I /? 



I /5 I /« 



I 2-* 



I 2$ 



I 3-.f 



I 36 



I -Wr 



I CT 
/// 



I C 
^22 



1 a 

335 



I a 



I s 



I fl 

£66 



I s 
777 



t B 



Zooo 



I 3 
3000 



1 fl 



J5SS 

Coals 



5555 



n a 

6666 



\N<n^tnf- 



S C 
7777 



BACK 



















































FENCE 


NO 


2 






















































I / 


I t 


I J 


I 4 


I ,5 


E ff 


I 7 


I 9 


r 10 


I /2 


I /■* 


I IS 


I /tf 


I n 


E 19 


I ^<j|r 2/ 


I 2-« 


I 27 


I ze 


I 29 


I J0|1 J/ 


I 32 


1 33 


I 34 


I 361.35 


1 •*! 


I 4/ 


I <r4' 


I «5 


1 Vi? 


I 49 


I s-/ 


/// 


I B 
222 


W^ 


I C 
444 


TL C 
SSS 


I c 
666 


777 


I B 
Bff 


u c 
Zooo 


30OO 




I a r c 

<*V* 4444 
iCci^s \ iCooTs 


n a 
/oaox 


U c U-Stsei Biooo 

„^.^ .•>c^>W Ctirwthi 
lOOO-X »f„™, ft„^A 


ICoaf' 











FRONT 



I ' 


r 2 


I J 


ir V 


ir JF 




r-y 


tt s 


S /0 


r /2 


z /« 


I /« 


I /f 


It /7 


Z /9 


I 20 


I 2/ 


I S4 


I 27 


r 28 


I ZiTL 30 


r jr/ 


r 32 


I 33 


X 34 


I jrs 


I 39 


r •*«> 


I •*/ 


E 44 


I ■« 


I O^ 


I 49 


u SI 


X a 
III 


I c 
Z2Z 


I a 

333 


I a 

444 


3 a 
sss 


I a 

666 


777 


I a 


Zooo 


I a 

300 o 


I a 

4O00 


X a 

3333 


m C 

3333 


s a 

3333 

1 


■x a 

3333 


BkicK 
Plali^ 













BACK 







































































FENCE 


N*> 


3 
























































m / 


m 


2 


m J 


m « 


IT s 


X. 


6 


a 


7 


S 


9 


r 


/(7 


m /2 


IT /« 


IT /« 


m 


/tf 


E /r 


m 19 


m 20 


M Zl 


n S4V. zy 


« ««m 


29 


Tt 30 


m 


J/ 


m: 31 


m. ^3 


m 34 


m 39 


m J9 


IT -^O 


m 41 


m ,»♦ 


m -#5 


n: *e 


It •« 


II J/ It a 
III 


M a 

Z2Z 


TSL C 
333 


K c 

ail 


nr c 
sss 


m c 
e6i 


m c n c 
777 «*^ 


m c 
zooo 


in c 

3000 


■wr c 

4C00 


m c 

4OO0 


Z32Z 


s c 

2222 


2222 


T a 

2222 




*>d' 















































































FRONT 


























































m / 

: 


r 


m 2 




m > 


E 


• 4 


m f 


DC < 


m 7 


nr 


9 


m 


/o 


n /2 


DI 14 


E /J 


E 


/5 


m /7 


B /9 


71 ZO 


IE 2/ 


m 24 


It 27 


m £« 


m 29 


nr JO 


IT J/ 


m J2 


nr 33 


m 34 


m j£ 


TSL 3i' 


m. 4o 


m ■*/ 


B iK" 


m •« 


m •»* 


m »» 


m SI 


/// 


IT c 


JrJ5 


IT B 
444 


sss 


w a 
S6i 


E C 
777 






sooo 


X a 

7777 


I c 

III! 


Tsr a 
nil 


V a 
nil 


SItel 
l/Aiil- 
Mot 


Y , 
Hint 


5/*c/, 
fiiinf 










iiL 




























































BACK 

























































NS I Dulch Pracess tfhi/e Leac/ 

N' 2 QuicKffvcess mte Lead 

ms Zinc Oxii/e 

N' 4 5ub/imed mi/& lead 

HSSSubl/med B/i/e lead 

A" 6 Litfiopone 

fJ" 7 Zinc Lead fThi/e. 



N°90rande M'neral/fmerican 
V'/O /^eiflead 
N'/ZBridhtPed Oxide Ceza} 
M'/4 li'enehan Red 
N'/SFr/'nces Aietal/ic Brown 
N'/6 Uptural Gmphlte 
N'l7^cheson Gmphire 



N'l9Lamb BlacK 
N'2o/i'i//Sir Chaivoaf 
N' 21 Gas Gerban B/ac^ 
//■'Sffrench Ye//air Oc/irt. 
N'Z7Bar(,iks Nafi/ra/ 
M'ZeBonj/ts Fi«cipi/i!/ed 
N°29Caf:.Carb. Ofhitin^) 



N°30Ca/c Cart Frec}pi/a/ed 
N'3lCa/ciiim Su/phafe (Gupsum) 
N'32China C/ai^ (kaolin) 
N°SS/4shes/i'ne(Slficcre Magnesium) 
N'34i4merKan Ivriril/ionCChnmeScar/ef) 
N'JUMed Cbrame Velhiy 
f^'SgZinc Chroma/e 



fi°40Zinc 9 Buriom Chvmo/e 
N'4I Chrome Green (Blx Tone) 
/l'W4fri/ssiei7 BJueCSfimu/afl've') 
N'4S/nhibi/!iie Pr:/ssian B/i/e 
V'4ff U/tramarine B/iie 
N'^gZmc SUac/GrDmare 
M'Sl^a^neffc B/ac/C Oxide 



f/'905fro:^l)/-lampBlaclf&m^mth^pf8-0n/crN<>2zz B/ock /nhibifiye Pain& 

f/'lOO " '■ Carbon " • »-.,,, N'333 tVhilS 

mooo Cfmme Pesma/t in a/ U'444 Green - ' 

>/' £000 /Cuat Zinc Oiroma/e /rfw/ fxdoder H'sss B/ac/r S/imo/afi're /&//wS 

N'JOOO / " lead > • / ■ /- //'See Brown 

^'4000/ ' fiedlead / . - //°7n fVhi/B 

iV' /// Braifr). /n/iib/fife Pain^ N'SSS Green 



N'llll Green S/pa&iaf'G'fbmu/a 
/f'2222 Red ' 
V3S33 Blxk '■ '■ 
1^04444^4. Sxc/uder /iirt 
lil'SSSS CoolTdr Pain/- 
fj*6666 Specio/ Paint 
tJ'7777 Special G/ Painf- 



Carbon 
Manganese 



Pho sphoroia 



^na/if3is of ,5/Vg/ in P/a/is 

N'Ifenca ll''2Fertcs N'SFtnc'a H'4^cm_' 

0t<.<r'rtrS/&' 9L'/fr' ^ftoflh ^r* Iran 

. Oe .16 OS I S Tad 

' ^ 3S ■ 'f^ U/mTriycs 

.oe ■ oz ops 



Su lphur 



.OS 



,024 



Soci al Btntmti fyrcialOurtM 



rtfa< 



H'SXmnce 



Inn 



Soellert'xt^ 



M'e nince 



sift 



Foman Numerals 
y^rai>ic Numerals ■■ 



Class of SAsal 
Number a f Pt/nt 



'B"= 8/oc/rPlaret tyHh 3aa/e 
C' Piclfeled P/aAs 



P/a/bs piclTe/et^ in Si/lphuric i^cid trare used Pirvo^houl- on Me pi^menls up /o '31, OSin^ a defina/6 
spreading ra/e al 9oo Sg.ft per ^allan- I'n applifing Pie crain/: ^bofe ^is number, cleaned pla/ls 
tvsre used nilh the defina/i spreaai'i>^ ra/a as oboi'e..and h/odrpJa/isn'ere usad>"»'ouron<f spragdi nfj rali . 



Excluding and Rust Inhibiting Proper- 
ties of Paint Pigments for the 
Protection of Steel 
and Iron 



By HENRY A. GARDNER 




PRESENTED BEFORE THE FORTIETH ANNUAL CONVENTION OF THE 

MASTER CAR AND LOCOMOTIVE PAINTERS' ASSOCIATION 

OF THE UNITED STATES AND CANADA 

NIAGARA FALLS, NEW YORK, SEPTEMBER 14, 1909 



1 



X 



'/ 



ly 



Cla.^, 245 781 
AUG 23 1909 



■~> 



L 



PREFACE 



The master painter will find herein a 
statement of the results obtained in the 
most recent study into the corrosion of iron 
and the development of protective coatings 
for the protection of iron. It is sincerely 
hoped that this pamphlet will be of con- 
siderable value to him in his work. 

HENRY A. GARDNER 



CHAPTER I 
Results in Recent Testing of Pigments 

The many theories, regarding the causes Study of 
of the corrosion of iron, advanced during the Corrosion 
last decade, have stimulated a great amount Necessary 
of original research on this subject by vari- wKen Designing 
ous investigators. In the course of these in- Protective 
vestigations the subject of protective coat- Coatings 
ings for iron and steel naturally has been 
brought into prominence and is receiving a 
considerable amount of attention. 

The study of protective coatings for iron 
and steel, converselv, has led manv interested 
paint manufacturers and users of painting ma- 
terials to make a closer study of the causes of 
corrosion in order that thev mav know how 
to make and use better paints for protecting 
steel. In so doing, they have discovered that 
the two subjects are intimately connected and 
vitally important to each other. 

No attempt will be made to cover the sub- 
ject of the painting of steel cars or locomotives, 
or to outline any method for so doing, but the 
object of this paper is to bring before 3^ou as 
]\Iaster Painters, entirely new light upon the 
subject of pigments and their properties and 
values, so that you may, yourselves, select with 
good judgment the proper pigments to use for 
various purposes. If, in the past, you have 
been using pigments which are poisonous to 

5 



steel and which cause active corrosion, vou 
should know it, and if, in the future, you can 
select pigments which are antiseptics and pre- 
ventives of rust, you should use them. 

A series of very interesting and instruc- 
tive researches into the nature of the various 
paint pigments used in the painting of iron 
and steel, as a determining factor in the cor- 
rosion of iron, were recently made, and, as a 
result of these investigations, it has been pos- 
sible for certain laws to be formulated, regard- 
ing the value of these pigments. Through 
a previous bulletin of the Scientific Section, 
namely, the ''Preliminary Report on Steel 
Test Fences," the paint trade at large was 
Results of ii^formed of these investigations, but the 
Recent ^^sults were withheld tentatively for the rea- 
Tests on ^^^ ^^^^ ^^^ Scientific Section had no desire 
Nature o{ ^^ publish any information, no matter how re- 
Pigments li^t>le the source from which it was obtained, 
without having absolute verification of results. 
The tests referred to were made upon fifty 
pigments largely used in the fabrication of 
paints, in order to determine which possess 
stimulative, which inert, and which inhibitive 
characteristics when in contact with steel in 
the presence of water. Bulletin No. 35, by Al- 
lerton S. Cushman, one of the foremost inves- 
tigators in this line of research, was recently 
issued by the Ofiice of Public Roads of the 
United States Department of Agriculture, and 
the results of these tests were published there- 
in. 

6 



The paint manufacturer has drawn atten- 
tion to the fact that some of these pigments 
which, in water, cause marked corrosion, when 
painted out in oil, give steel and iron immun- 
ity from corrosion for some period. The ex- 
cluding value of such pigments may account 
for their protection for a certain time. How- 
ever, when the film of oil has been destroyed, 
the pigment is subject to the moisture which 
acts to stimulate corrosion. 

The following table is printed in Bulletin 
No. 35, by Allerton S. Cushman, of the United 
States Department of Agriculture: 

BASIC CLASSIFICATION OF PIGMENTS 

INHIBITORS INDETERMINATES STIMULATORS 

Zinc Lead Chromate White Lead (quick pro- Lamp Black 

Zinc Oxide cess, Basic Carbonate Precipitated Barium Sul- 

Zinc Chromate Sublimed Lead (Basic Sul- phate (Blanc Fixe) 

Zinc and Barium Chro- phate) Ocher 

mate SubHmed Blue Lead Bright Red Oxide 

Zinc Lead White Lithopone Carbon Black 

Prussian Blue (Inhibitive) Orange Mineral (Ameri- Graphite No. 2 
Chrome Green (Blue tone) can) Barium Sulphate (Barytes) 

White Lead (Dutch pro- Red Lead Graphite No. 1 

cess) Litharge Chinese Blue (Stimulative 

Ultramarine Blue Venetian Red Prussian) 

Willow Charcoal Prince's Metallic Brown 

Calcium Carbonate (Whit- 
ing) 

Calcium Carbonate (pre- 
cipitated) 

Calcium Sulphate 

China Clay- 
Asbestine 

American Vermilion 

Medium Chrome Yellow 

The following table gives the results ob- 
tained by the dififerent investigators in determ- 
ining by an accelerated test the relation of the 
various paint pigments in their effect on iron 
and steel in the presence of water. The losses 

7 



LOSS OF STEEL IN GRAMS IN TESTS CARRIED OUT ON PIGMENTS 
TO ASCERTAIN THEIR VALUE AS RUST INHIBITORS 



Gardner Cushman Walker Cushman Walker Aver'ge 

P. H. W. H. 

Pigment No. 1 Nos. 1 & 2 No. 2 No. 2 No. 1 

20 days 10 days 1% days 10 days 

1 Zinc Chromate 0050 .0300 .0094 .0130 .0396 .0194 

2 Zinc and Barium Chromate . . .0153 .0468 .0034 .0140 .0351 .0229 

3 Zinc and Lead Chromate . . . .0094 .0277 .0153 .0085 .0620 .0246 

4 Zinc Oxide .1524 .0296 .1002 .0085 .0504 .0682 

5 Zinc Lead White 0842 .1712 .0515 .0856 .0456 .0876 

6 Barium Chromate 2333 .0101 .0429 .0094 .1932 .0978 

7 Ultramarine Blue 0247 .3185 .0137 .1865 .0496 .1186 

8 Chrome Green (blue tone) , . .0860 .2269 .0548 .1240 .2346 .1453 

9 Prussian Blue Inhibitive ... .1438 .2267 .0448 .1130 .2671 .1591 

10 Lithopone 0160 .3791 .1274 .1792 . . . .1754 

11 Willow Charcoal 1694 .2795 .1439 .1362 .2110 .1880 

12 Litharge 4325 .1932 .0309 .1584 . . . .2038 

13 Dutch Process White Lead . . .2040 .2895 .1781 .1150 .2743 .2122 

14 Quick Process White Lead . . .2120 .3352 .1288 .1848 .2274 .2176 

15 Calcium Sulphate 3966 .2143 .1759 .1597 .2174 .2328 

16 Prince's Metallic Brown . . .3774 .2620 .1983 .1408 .1974 .2352 

17 Orange Mineral French 3950 .2724 .1495 .1467 .2526 .2432 

18 Calcium Carbonate (Whiting). .3828 .3620 .1384 .2380 .1208 .2484 

19 Sublimed Blue Lead 3177 .3425 .1001 .2365 - . . .2492 

20 Lemon Chrome Yellow 2767 .4067 .1365 .1972 ... .2543 

21 Orange Chrome Yellow 2826 .4203 .1700 .1907 .2150 .2557 

22 Medium Chrome Yellow 4090 .3767 .1319 .1763 .2288 .2645 

23 Chrome Green (yellow) 3265 .3670 .1348 .1453 .3521 .2651 

24 Venetian Red 2682 .4756 .1955 .2375 .1564 .2666 

25 Bone Black 3392 .3245 .0921 .1413 .4401 .2674 

26 Asbestine 2394 .4025 .1748 .2240 .3405 .2762 

27 Keystone Filler 3560 .4651 .1366 .3349 .1481 .2881 

28 Orange Mineral American . . . .4416 .4336 .1719 .2065 .2315 .2970 

29 Umber 1365 .5961 .1498 .3817 .2403 .3009 

30 China Clay 3493 .4770 .1248 .2445 .3212 .3034 

31 Calcium Carbonate Precipitated .3574 .4910 .1828 .2625 .2616 .3111 

32 Red Lead 3112 .3555 .1495 .1717 .5707 .3117 

33 Prussian Blue Neutral 3584 .4463 .1218 .2415 .4173 .3171 

34 Indian Red 3546 .3739 .2617 .1905 .4334 .3228 

35 American Vermilion 4328 .4147 .2612 .1877 .3387 .3270 

36 Sublimed Lead 4176 .5856 .0982 .2372 .3116 .3300 

37 Sienna 2876 .5432 .2949 .3085 .4462 .3761 

38 Naples Yellow 6482 .4800 .1512 .2347 .3846 .3797 

39 Prussian Blue Stimulative . . . .5113 .4559 .2055 .2195 .5202 .3825 

40 Mineral Black 3050 .8018 .2017 .3529 .3353 .3993 

41 Barytes 4454 .5883 .2547 .3841 .5636 .4472 

42 Natural Graphite 4342 .5437 .2606 .3173 .7165 .4545 

43 Bright Red Oxide .3878 .7896 .2920 .3707 .4429 .4566 

44 Acheson Graphite 5262 .6337 .3723 .2789 .5095 .4641 

45 Ochre 4022 .8408 .2119 .4315 - . . .4716 

46 Carbonith White 2655 7152 .4904 

47 Carbon Black 5003 .6955 .4069 .3751 .5716 .5099 

48 Precipitated Blanc Fixe . . . .5247 .8806 .3132 .5085 .5064 .5467 

49 Lamp Black 7180 1.3098 .2838 .7096 .6257 .7294 

8 



in weight measure the amount of corrosion. 
The most inhibitive head the Hst and the most 
stimulative are at the bottom. 



CHAPTER II 

Pigments in Aqueous vs. Oil Medium 

Objections Some objections were made by chemists 

Offered to to the tests of the different pigments in water 
TKese Tests medimn, on the ground that pigments which 
might stimulate corrosion in the presence of 
water would not do so in oil medium. Claims 
were made that oil acts as an envelope for 
the pigment particles, and being a non-con- 
ductor of electricity, prevents any electrolytic 
action taking place on the steel plates upon 
which they are painted out. 
rp yi ^ These objections suggested some rather 

. /t.. interesting- experiments. Upon several slides 

with Pigments ^ ^ i j r 

• M-i of srlass, such as are used for mountmg micro- 

in Uil . • 1 ^ • 

scopic specmiens, were pamted out various 
pigments ground in oil. Upon these plates of 
glass thus painted and after they were prop- 
erly dried, were firmly secured small strips 
of copper at either end. To the ends of the 
^ . strips of copper were attached the wires of an 
Results Lonfirm ^^^-^^^^ ^^^ ^^jj ^^^^ ^^is circuit was placed 
Previous Work ^ ^^^^ delicate galvanometer. It was found 

that absolutely no current flowed through the 
paint film, and the galvanometer needle re- 
mained in its original position, at zero. 

The glass slides were then removed from 
the apparatus and immersed in water for a 
while, during which time they were penetrat- 

10 



ed by the water to a certain extent, thus du- 
pHcating in a quick way the action of rain- 
storms upon paint coatings over an extended 
period. The sHdes were removed from the 
water and, after being carefully wiped off, 
were again connected up in the apparatus. 

It was then found that certain pigments Conductivity of 
which are good conductors of electricity per- ^vloist Films by 
mitted the current to flow, and the galvano- Stimulative 
meter needle was deflected to quite an extent, pigj^ents 
On the other hand, in the case of pigments 
which are absolutely non-conductors of elec- Non- 
tricity, there was no movement of the needle. Conductivity of 
As would be expected, those pigments which Moist Films 
caused deflection of the galvanometer, such as ^f Inliibitive 
the carbonaceous group, were in the active Pigments 
stimulative class, while those which prevented 
the deflection of the galvanometer needle were 
in the inhibitive class. These results confirm 
Dr. Cushman's results regarding the nature of 
such pigments. Corrosion in structural steel 
in situ appears to be dependent largely upon 
what Dr. Thompson, in commenting on the 
work of Cushman, Walker and others, has 
aptly designated "auto-electrolysis" — that is, 
electrolysis due to currents set up between 
areas having different potentials in the material 
itself. These currents require the presence of 
an electrolyte to serve as a conductor and thus 
complete the electrical circuit. It thus appears 
probable that a paint film which, when moist- 
ened, becomes a good conductor of electricity, 
mav serve as an active aid to corrosion through 
this physical quality alone. 

11 



CHAPTER III 
Results of Inspection of Steel Test Fences 

As explained in the "Preliminary Report 
on Steel Test Fences," in order to make a prac- 
tical field test of the value of various pigments, 
it was decided by the Paint Manufacturers' As- 
sociation to erect steel test fences at Atlantic 
City, upon which to paint out in oil medium all 
the pigments which previously had been tested 
out by so many investigators in aqueous medi- 
um. 

The work was carried out with the great- 
Steel Test est care by the Scientific Section* and was under 
Fences for ^^^^ supervision of Committee E, on Preserva- 
P t' 1 Field ^^^^ Coatings, and Committee U, on Iron and 

Steel, of the American Society for Testing Ma- 

lestol Value ,._, ^, ^ TV/r...„^ t)„:„.„.„. a •_.• 



ofV 



arious 



terials. The Master Painters' Association of 
Pennsylvania was also represented in the work. 
Pigments j^ the front of this book will be found a 

chart of the fences, showing the placement of 
every panel and giving the formula of the paint 
applied thereon. This chart will be of con- 
siderable value to anyone desirous of making 
a personal investigation of the fence. 

A recent inspection of the fences indicated 
that it was too early to make a report, but a 
few observations recently made, may not be 
out of place at this time. 

12 



It was found that the white lead and zinc Condition of 
oxide pigments appeared to have thus far given White Lead, 
excellent protection to the steel and iron upon Zinc Oxide, 
which the}^ were painted. The pure white Oxide of Iron 
lead, however, has shown tendency to chalk, Paints 
while in some cases the zinc oxide has shown 
tendency toward checking*. The red iron ox- 
ides applied to the steel plates seemed to be in 
good condition, with the possible exception of 
Venetian red on which there seemed to be a 
very slight exudation or leaching out of the 
calcium sulphate contained in this pigment. 

An examination of the graphite, lamp Condition of 
black and carbon black films showed that it Carbonaceous 
was too early to report on their value. These Paints 
films are still intact and the color prevents 
close examination of the underlying surface. 
However, it was observed that wherever the 
plates, which were painted with these pig- 
ments, had been abraded to the least degree, 
very active corrosion had started, and appeared 
to be spreading underneath the paint coating. 

The plates painted with' red lead were in Inhlbitive 
excellent condition, as were also those painted Pigments 
with zinc chromate and zinc-and-barium chro- Standing 
mate. In the case of the plates painted with ^f/Q\\ 
zinc chromate, several abrasions made at the «• 

time of erecting the fence disclosed the clean 
steel plate which had suffered practically no 
corrosion. This, presumably, is due to the 
fact that zinc chromate being slightly soluble 
had kept the abraded places in a passive state 
and prevented any rust forming thereon. The 

13 



Value of plates painted with chromium resinate seem 
Cliromium to be in excellent condition, and the high effi- 
Pigments ciency of this pigment as a water excluder may 
prove it to be a valuable ingredient of a pro- 
tective paint coating. 
Prime The plates, which were primed with vari- 

Coaters ous inhibitive pigments and topped with the 
same second-coater, have not shown as yet 
any definite results which would indicate which 
pigment to use as a prime coating material. 
Defects The plates, which were coated with red 

Observed on lead and second-coated with bitumen and coal 
Coal Tar Paints tar paints disclosed a most marked alligatoring 

of the top coats, through which the red lead 
used as a prime coater could be distinctly seen. 
Unequal expansion of the two coats is probab- 
ly responsible for this fault. 
M k d R St Those plates painted with calcium sul- 

. 1 . phate (eypsum) showed the most marked cor- 

Acceleration on i vfeji , . . ^- r 

PI Coated ^osion, the plates showmg a brown coatmg o± 

l^j^ oxide of iron working itself completely under 



Wll 



Gypsum the coating. 

It was noticed that calcium carbonate and 
Natural and barium sulphate, both in the precipitated form, 
Artificial as apphed to the steel panels, exhibited con- 
Barium siderable chalking, while calcium carbonate 
Sulfate and barium sulphate in their natural state, as 
and Calcium whiting and barytes respectively, were stand- 
Carbonate ing up much better, no chalking being evident. 
The precipitated forms of calcium carbonate 
and barium sulphate gave the greatest hiding 
power, being quite opaque, while the natural 
forms, were very transparent. 

14 



The several samples of steel which were Rate of 
exposed unpainted after having been pickled Corrosion on 
showed varied degrees of corrosion, but it Various 
is too early as yet to report upon these plates. Unpainted 
However, those plates which were exposed un- Plates 
painted, but having the mill scale showed more 
rapid corrosion and more pitting than those 
plates not having the mill scale; in fact some 
of these plates having the mill scale corroded 
in certain spots in an extremely rapid way, 
leaving certain areas with the mill scale un- 
acted upon. The mill scale in this case would 
act as a surface upon which the hydrogen 
evolved during the electrolytic action which 
accompanies the process of corrosion could be 
catalyzed to form water, thus allowing the cor- 
rosion to proceed very rapidly. This bears 
out the statement of Dr. W. H. Walker, Prof, 
of Industrial Chemistry at the Mass. Inst, of 
Technology, regarding the function of oxygen 
in the corrosion of iron and the action of mill 
scale as a depolarizing surface.* 



*This recalls some recent work done by Dr. Walker 
in which he finds linseed oil to be, under certain conditions, 
an accelerator of corrosion. He found that when a sted 
or iron surface painted with linseed oil became abraded in 
any particular spot, corrosion would proceed more rapidly 
in the presence of the coating of oil than without the coat- 
ing. This he ascribes to the fact that the hydrogen, which is 
evolved during the corrosion is removed immediately by 
the linseed oil, which (being an unsaturated hydrocarbon) 
has an enormous power of absorbing the hydrogen and acts 
very much in the same way as mill scale in destroying the 
"electrolytic double layer," so-called. In the event, how- 
ever, of the linseed oil containing different pigments there 
is a marked difference in the ability of the linseed oil to re- 
move the hydrogen with sufficient rapidity to accelerate cor- 
rosion. 

15 



Wherever an abrasion appeared upon the 
paint coatings of the various panels, different 
results w^ere noted. In the case of panels 
w^hich w^ere painted w^ith certain stimulative 
materials, abrasions showed progressive cor- 
rosion had proceeded and pitting v^as evident, 
w^hile in the case of panels painted w^ith high 
powder inhibltive materials, the steel w^as in 
very good condition. 
Scratching ^^ order to give this new^ development in 

Plates to ^^^ Study of the corrosion of iron a practical 
Observe Action ^^^^ test, each plate on the steel test fences 
of Oil Coatings has recently been scratched at the lower right 

hand corner, using the same instrument in each 
case. The painted surfaces being thus abrad- 
ed, the progress of the corrosion will be care- 
fully watched and most interesting data may 
be recorded later on as regards the value of 
each pigment in linseed oil in checking any 
accelerative action which may be exerted by 
the linseed oil. 



16 



CHAPTER IV 

Excluding and Water-Resisting Properties 

of Paints 

Besides considering- the pigments as stim- 
ulators and inhibitors, a most careful study has 
been made by the Scientific Section as to the 
value of various pigments as excluders or mois- 
ture resisters. 

An excluding paint is one that has the g^^i^j^j-s ^nd 
property of excluding and preventing the ad- ^^^^^ Skedders 
mission of moisture to the steel, thus depriving 
the steel of the moisture which is essential to 
corrosion. A water-shedding paint is one 
which has the property, because of certain phy- 
sical characteristics, of shedding water, and 
plates painted with such paints often appear 
drv immediatelv after a rain storm. Pig- 
ments greasy and unctuous in nature make 
good water-shedding paints. They may or 
may not have excluding values. 

The excluding properties of a paint coat- Properties of 
ing are largely dependent upon the composi- Excluding 
tion of the vehicle. It has been proved be- Paints 
yond doubt that a vehicle the interstices of 
which are filled up with fused gum is superior 
in its water excluding propert.es. Some ex- 
cluders do not have the property of moisture 
shedding, and observations have been made of- 

17 



several plates painted with natural excluding 
materials which did not shed water, but which 
were the most perfect water excluders. Ordin- 
arily linseed oil, when painted out and dry, is 
neither an excluder nor a moisture resister, as 
the tackiness of the film will show after a rain 
storm. A peculiar blistering appearance is 
also shown on the surface, showing where rain 
drops have acted upon the vehicle and pene- 
trated through, leaving the coating soft and 
pliable and sometimes raising many blisters 
thereon. 
Water Sliedders Considerable value has been attached to 

Not Always certain protective coatings whose only real vir- 
Permanent tue was that of being able to resist the action 
of rain and water, but which would ultimatelv 
break down in a very rapid way, allowing deep 
penetration by the water. The water shedding 
pigments which we have mentioned as being 
greasy in nature or unctuous, serve sometimes, 
when made into paints, as good protective coat- 
ings for a time, but sooner or later fail com- 
pletely in their object. 

HTur • , It has often been asked, in what manner 

ow Moisture , ' . 

G Til ^\\ ^^^^ water penetrate a paint coating? When 
a P * t F'l ^^^ coating is comparatively new and the lin- 

oxyn intact, the water goes through probably 
in two ways : either by forming a solid solu- 
tion with the linoxyn coating itself and becom- 
ing a part of the paint, or by diffusing through 
the linoxyn, which is really a porous mem- 
brane. 

Thus it would appear that the use of dif- 

18 



ferent pigments would produce more or less Properties of 
permeable films, according to the proportion of Different 
space filled up in the vehicle. Pigments in 

That certain pigments do have the power Retarding 
of preventing to a certain extent more than Moisture 
others the admission of water through a paint Penetration 
coating, the following series of experiments 
seem to prove. 

A series of paint films were made from Films made of 
many of the pigments which were used in Paints Used on 
painting the Atlantic City test fence. These Steel Fences 
paints contained the pigment ground in two- 
thirds raw and one-third boiled oil, without 
drier, and the films were painted out in three- 
coat work, allowing ample time between each 
coat for proper drying. No method has yet 
been devised for securing paint films of abso- 
lutely the same thickness, but the greatest care 
was taken in making these films to have them 
all approximately the same thickness. 

Small bottles, like that shown in the illus- Arrangement of 
tration, were half filled with concentrated sul- Tests 
phuric acid and paint films were hermetically 
sealed over the mouths with Canada balsam. 
These bottles, numbered, were then accurately 
weighed on delicate chemical balances and af- 
terward exposed under a large bell jar, all at 
the same time. This bell jar was so fixed that it 
could be saturated with moisture and kept un- 
der constant temperature. At the end of a 
week the bottles were removed and carefully 
weighed again. The increase in weight indi- 
cated the amount of moisture which had pen- 

19 



etrated the film in each case and which was 
taken up by the sulphuric acid, by absorption. 




Results of Tht test was kept up for forty-nine days, 

Moisture niaking weighing-s every seven days. The fig- 
Absorption ures in the table indicate the amount, in 
Tests grams, of moisture taken up. The pigments 

20 



*' MOISTURE EXPERIMENTS'' 

FIGURES GIVEN EXPRESS GAIN IN WEIGHT, 
e. g., WATER ABSORBED 

7 days 14 days 21 days 28 days 35 days 49 days 

Iron Oxides (with 2% Zinc Chromate 

and 2% Chrome Resinate) .... 0.032 0.048 0.072 0.092 0.110 .140 

Dutch White Lead 0.040 0.078 0.111 0.162 0.187 .264 

White Lead and Zinc Oxide .... 0.043 0.081 0.115 0.163 0.192 .266 

China Clay 0.044 0.086 0.122 0.182 0.219 .317 

Whiting 0.044 0.079 0.114 0.167 0.197 .277 

Zinc Oxide, Barytes and Blanc Fixe 0.048 0.092 0.125 0.183 0.190 .290 

Zinc Lead White 0.049 0.095 0.130 0.181 0.211 .284 

Red Lead 0.049 0.092 0.130 0.187 0.215 .295 

Basic Sulphate-White Lead .... 0.049 0.092 0.128 0.185 0.213 .292 

Zinc Oxide and Whiting 0.060 0.110 0.156 0.221 0.256 .352 

Zinc Chromate . . 0.064 0.121 0.176 0.270 0.298 .417 

Barytes and Zinc Oxide 0.064 0.118 0.169 0.240 0.278 .386 

Zinc Oxide 0.065 0.122 0.172 0.244 0.285 .391 

Calcium Sulphate 0.066 0.140 0.212 0.313 0.377 .555 

American Vermilion 0.069 0.140 0.202 0.311 0.349 .501 

White Lead, Barytes and Blanc Fixe 0.074 0.137 0.200 0.294 0.344 .490 

Barytes 0.074 0.138 0.202 0.298 0.336 .466 

Willow Charcoal 0.077 0.154 0.236 0.378 0.459 .694 

Lithopone 0.083 0.156 0.228 0.332 0.380 .550 

Carbon Black 0.084 0.168 0.250 0.391 0.448 .654 

Lead and Zinc Chromate . ..... 0.086 0.161 0.226 0.319 0.369 .497 

Chinese Blue Stimulative 0.092 0.185 0.276 0.405 0.470 .671 

Venetian Red 0.093 0.190 0.279 0.418 0.508 .770 

Natural Graphite 0.104 0.223 0.350 0.539 0.632 .951 

Medium Chrome Yellow 0.106 0.207 0.300 0.429 0.505 .725 

Bright Red Oxide 0.116 0.240 0.365 0.548 0.662 .976 

Barium and Zinc Chromate 0.116 0.211 0.298 0.430 0.481 .660 

Ultramarine 0.119 0.230 0.336 0.484 0.578 .814 

Prussian Blue Inhibitive 0.125 0.246 0.361 0.521 0.619 .733 

Raw Linseed Oil 0.143 0.300 0.449 0.679 0.803 L201 

Lampblack . 0.199 0.411 0.641 1.033 L234 1.873 

Blanc Fixe 0.210 0.472 0.744 1.144 1.414 1.944 

Carried out by H. A. Gardner and Zoltan de Horvath 

21 



have been arranged with regard to the most 
perfect excluders at the top, followed by those 
which are less efficient as excluders. As will 
be noted in the table, the tests all the way 
through were confirmed at each weighing. At 
the head of the list stands iron oxide, which 
contains chromium resinate in small propor- 
tion. It will be found by careful observation 
of the list of pigments in the table that iron 
oxide by itself falls near the middle, but by 
the addition of 2 per cent, of chromium resin- 
ate, which acts as a gum to seal up the inter- 
stices of the pigment, this pigment has been 
rendered the most excellent water excluder 
that we have. 

Practical, as well as laboratory, tests have 
brought out the new information which is pre- 
sented to you, and a study of the tables con- 
tained in this book will doubtless prove of value 
to all interested in paints for the protection of 
iron and steel. 



22 



SUPPLEMENT 



The steel wire fences erected in Pittsburg, 
under the direction of Dr. Cushman, and paint- 
ed by the Scientific Section, are showing some 
interesting results. The cut shows a section 
of wire painted with a stimulative carbon- 
aceous paint. The marked corrosion going 
on seems to indicate that the most inhibitive 
paints only should be used for painting iron 

and steel. 

A further description of the steel wire 
panels may be found in Bulletin No. 35, by Dr. 
Cushman, of the Office of Public Roads, U. S. 
Dept. of Agriculture. 



24 




c 

m 
C 
O 
a 
o 

03 
C 
O 

;h 
<A 
O 

> 

• I-H 

OS 



-(J 






OJ 

ft 

0) 



O 

c 
o 

• rl 

o 



c 



